1. Field of the Invention
The present invention relates to a method of and an apparatus for manufacturing a belt for use in a continuously variable transmission.
2. Description of the Related Art
There is known a belt for use in a continuously variable transmission which comprises an annular hoop of laminated metal elements each having a body and a head joined thereto with a pair of recesses defined therebetween, and a pair of rings inserted respectively in the recesses and each comprising a plurality of laminated metal web-shaped rings.
The above hoop is manufactured by forming elements on an element production line, forming laminated rings on a ring production line, and assembling the elements and the laminated rings together on a belt assembly line.
On the element production line, elements of desired shape are blanked out of a metal plate, tempered, and then finished by grinding. On the ring production line, sheet-like rings of desired shape are rolled from ring-shaped metal sheets, then subjected to a solution treatment, corrected for their circumferential length, aged and nitrided, and then laminated into a ring.
One known belt assembling process for being carried out on the belt assembly line is disclosed in Japanese laid-open utility model publication No. 59-22344. According to the disclosed belt assembling process, an annular hoop of laminated elements is held in an annular support groove defined in a block stand. Recesses defined in the respective elements are successively arranged in an annular pattern, and are open on one side of the hoop. Then, a laminated ring is pushed into the successively arranged recesses. At this time, the laminated ring is guided by an annular guide having a tapered guide surface whose diameter is progressively larger in the direction in which the laminated ring is inserted into the recesses, so that the laminated ring has its diameter progressively increased as it is guided into the recesses.
The above conventional process of manufacturing a belt for a continuously variable transmission, or particularly the known belt assembling process, suffers the following problem: If gaps smaller than the thickness of an element are created between the elements that are placed in the support groove in the block stand due to thickness errors of the elements, then since no element can be inserted into the gaps to bring the elements into intimate contact with each other, the elements bundled together by the laminated ring tend to be spaced excessively from each other, resulting in poor belt performance.
According to the above conventional belt manufacturing process, if the head of each element has dimples and holes defined in both face and back sides thereof (see, for example, Japanese laid-open patent publication No. 63-57942 and Japanese utility model publication No. 5-34354), then the dimples present an obstacle making it difficult to hold a desired number of elements in the support groove in the block stand.
Furthermore, according to the above conventional belt manufacturing process, inasmuch as the laminated ring is increased in diameter by the annular guide with the tapered guide surface, if the laminated ring has circumferential length variations and its circumferential length is relatively small, then it is difficult for the laminated ring to be increased in diameter by the tapered guide surface. If the laminated ring whose circumferential length is relatively small is forcibly slid along the tapered guide surface to increase its diameter, then the laminated ring may possibly be damaged.
Elements that are manufactured on the element production line may be bent or damaged, or laminated rings manufactured on the ring production line may be in a poorly laminated state. If elements are bent or damaged or laminated rings are in a poorly laminated state, then continuously variable transmission belts assembled on the belt assembly line are of lowered quality.
One solution is to inspect continuously variable transmission belts assembled on the belt assembly line for their assembled state. For example, clearances between elements bundled by laminated rings of a continuously variable transmission belt are selected at some locations, and visually measured by a manually applied thickness gage. If the measured clearances are smaller than a predetermined dimension, then the continuously variable transmission belt is judged as being in a well assembled state. If the measured clearances are greater than the predetermined dimension, then the continuously variable transmission belt is judged as being in a poorly assembled state and hence is rejected.
The above inspection process is disadvantageous in that the inspection process is not efficient as it involves the manual application of the thickness gage and tends to suffer accuracy variations due to inspection personnel differences and different skill levels. In addition, if the clearances between elements which have not been measured are not acceptable or the number of elements that make up a continuously variable transmission belt is not sufficient, then the performance of the continuously variable transmission belt is adversely affected.
With the above inspection process, furthermore, it is difficult to identify causes of defective assembled states. Specifically, continuously variable transmission belts may be assembled defectively because some elements are bent or cracked or laminated rings are not in a well laminated state. Any of these causes cannot easily be identified simply by measuring the clearances between elements according to the above inspection process. Therefore, when a continuously variable transmission belt is judged as being assembled defectively, the judgment cannot quickly and smoothly be reflected in adjustments of various apparatus of the element production line and the ring production line.
Still another problem of the above inspection process is that even if produced elements include defective elements, since continuously variable transmission belts need to be actually assembled in order to be inspected according to the inspection process, some of the assembled continuously variable transmission belts cannot be delivered as products due to those defective elements, and hence the efficiency of the belt assembly line is low.
It is therefore an object of the present invention to provide a method of manufacturing a belt for use in a continuously variable transmission efficiently in a well assembled state by rejecting in advance defective elements and laminated rings.
To achieve the above object, there is provided in accordance with an aspect of the present invention a method of manufacturing a belt for use in a continuously variable transmission which comprises an annular hoop of laminated metal elements each having a body and a head joined thereto with a pair of recesses defined therebetween, and a pair of rings inserted respectively in the recesses and each comprising a plurality of laminated metal web-shaped rings, with an element production line for producing the elements through a plurality of processes, a ring production line for producing the laminated rings through a plurality of processes parallel to the element production line, and a belt assembly line joined to the element production line and the ring production line, for bundling the elements with the laminated rings thereby to assemble the belt. The method comprises the steps of inspecting the elements for a produced state thereof at a terminal end of the element production line and sending those elements which are judged as acceptable to the belt assembly line, inspecting the laminated rings for a laminated state thereof at a terminal end of the ring production line and sending those laminated rings which are judged as acceptable to the belt assembly line, and inspecting belts for an assembled state at the belt assembly line and delivering those belts which are judged as acceptable as products.
On the element production line, the elements are produced through the plurality of processes, and then inspected. In the element inspecting step, the elements are inspected for bends, scratches, cracks, etc., and those elements that are judged as acceptable are delivered to the belt assembly line. If produced elements are judged as defective in the element inspecting step, then the inspected data can easily be reflected in adjustments of various apparatus on the element production line for increasing the accuracy with which elements are produced. Only those elements which are produced with desired accuracy can be sent to the belt assembly line.
On the ring production line, after the rings are assembled, they are inspected. In the ring inspecting step, the rings are inspected for the number of web-shaped rings and the degree to which the web-shaped rings are held in close contact with each other, and only those laminated rings that are judged as acceptable are delivered to the belt assembly line. If produced laminated rings are judged as defective in the ring inspecting step, then the inspected data can easily be reflected in adjustments of various apparatus on the ring production line for increasing the accuracy with which laminated rings are produced. Only those laminated rings which are produced with desired accuracy can be sent to the belt assembly line.
On the belt assembly line, the efficiency with which to produce belts is increased because belts are assembled of acceptable elements and acceptable laminated rings.
On the belt assembly line, after a belt is assembled, the belt is inspected for quality. When the belt is assembled, since the elements and the laminated rings thereof have already been judged as acceptable in the element inspecting step and the ring inspecting step, the number of any defectively assembled belts is extremely small. If an assembled belt is judged as defective in the belt inspecting step, then since the elements and the laminated rings thereof have already been judged as acceptable, it can easily be determined that the defect of the assembled belt is caused on the belt assembly line. The inspected data can thus easily be reflected in adjustments of various apparatus on the belt assembly line.
Another object of the present invention is to provide a method of and an apparatus for manufacturing a belt for use in a continuously variable transmission by bundling elements closely held together with laminated rings, the number of elements depending on the circumferential length of the laminated rings, so that the belt can easily be assembled with high accuracy.
To achieve the above object, there is provided in accordance with another aspect of the present invention a method of manufacturing a belt for use in a continuously variable transmission which comprises an annular hoop of laminated metal elements each having a body and a head joined thereto with a pair of recesses defined therebetween, and a pair of rings inserted respectively in the recesses and each comprising a plurality of laminated metal web-shaped rings, comprising the steps of laminating a plurality of elements as an annular hoop with the bodies positioned inwardly, and pushing the elements in a direction from the heads toward the bodies to clamp the elements in close contact with each other, radially spreading the laminated rings which confront the respective recesses in the clamped elements to a diameter positionally corresponding to the recesses fully across the laminated rings, and pressing the radially spread laminated rings into the respective recesses in the elements.
According to the above method, a plurality of elements are laminated as an annular hoop and clamped with the bodies positioned inwardly. At this time, the elements are pushed in a direction from the heads toward the bodies to clamp the elements in close contact with each other. Thus, no clearances are produced between the elements, and the diameter of the recesses in the successive elements that are laminated is sufficiently reduced.
Then, the laminated rings which confront the respective recesses in the clamped elements are radially spread to a diameter positionally corresponding to the recesses fully across the laminated rings. Since the laminated rings are radially spread fully thereacross, the laminated rings can sufficiently be radially spread without damage as compared with a conventional process in which the laminated rings are radially spread as they are moved along a slanted surface.
Inasmuch as the diameter of the recesses in the successive elements that are laminated is sufficiently reduced, even if the distance by which the laminated rings are radially spread is relatively small, the laminated rings can easily be inserted into the successive recesses in the clamped elements, so that a highly accurate belt can be assembled.
The step of pressing the radially spread laminated rings into the respective recesses in the elements should preferably comprise the step of detecting a load applied the laminated rings while pressing the radially spread laminated rings into the respective recesses in the elements, for thereby inspecting whether the belt is acceptable or not. For example, if the laminated rings cause scoring in the recesses or the diameters of the laminated rings do not match those of the recesses, then the laminated rings is subjected to an excessively large load. Therefore, defective laminated rings can be rejected by detecting such as load.
According to still another aspect of the present invention, there is also provided an apparatus for manufacturing a belt for use in a continuously variable transmission which comprises an annular hoop of laminated metal elements each having a body and a head joined thereto with a pair of recesses defined therebetween, and a pair of rings inserted respectively in the recesses and each comprising a plurality of laminated metal web-shaped rings, comprising element holding means for holding the annular hoop of laminated metal elements with the bodies positioned inwardly and the recesses opening vertically, for movement in a direction from the heads to the bodies, element pressing means disposed in the element holding means, for pressing the annular hoop of laminated metal elements in the direction from the heads to the bodies thereby to bring the elements into close contact with each other, a first collet disposed below the element holding means, for placing one of the laminated rings therearound and radially spreading the one of the laminated rings, first spreading means for radially spreading the first collet to spread the laminated ring placed around the first collet to a diameter positionally corresponding to one of the recesses in the annular hoop of elements fully across the laminated ring, a second collet disposed above the element holding means, for placing the other of the laminated rings therearound and radially spreading the other of the laminated rings, second spreading means for radially spreading the second collet to spread the laminated ring placed around the second collet to a diameter positionally corresponding to the other of the recesses in the annular hoop of elements fully across the laminated ring, first ring pressing means for abutting against a lower edge of the laminated ring placed around the first collet and pressing the laminated ring into the one of the recesses, and second ring pressing means for abutting against an upper edge of the laminated ring placed around the second collet and pressing the laminated ring into the other of the recesses.
The element holding means holds the annular hoop of laminated metal elements for movement in a direction from the heads to the bodies. At this time, the bodies are positioned inwardly and the recesses opening vertically, and the laminated rings can be inserted into the successive recesses. The element pressing means disposed in the element holding means presses the annular hoop of laminated metal elements in the direction from the heads to the bodies. The elements are displaced in the direction from the heads to the bodies and brought into close contact with each other, so that the elements are securely clamped in position. Since the elements are brought into close contact with each other, the diameter of the successive recesses is sufficiently reduced. The element holding means holds the elements while moving them in the direction from the heads to the bodies, after which the element pressing means clamp the elements. Consequently, when the elements are laminated before they are clamped, certain clearances may be provided between the elements. The elements can thus be laminated with ease even if dimples and holes, for example, are defined in both surfaces of the elements. Thereafter, the elements are displaced in the direction from the heads to the bodies, so that the elements can easily be clamped with the dimples and the holes closely held together.
One of the laminated rings is placed around the first collet, and positioned in alignment with the successive recesses, which are open downwardly, in the clamped elements. The first spreading means radially spreads the first collet to spread the laminated ring placed around the first collet to a diameter positionally corresponding to the one of the recesses in the annular hoop of elements fully across the laminated ring.
Similarly, the other laminated ring is placed around the second collet, and positioned in alignment with the successive recesses, which are open upwardly, in the clamped elements. The second spreading means radially spreads the second collet to spread the laminated ring placed around the second collet to a diameter positionally corresponding to the other of the recesses in the annular hoop of elements fully across the laminated ring.
Since the laminated rings are supported by the respective collets and radially spread by the spreading means through the collets, each of the laminated rings can easily be radially spread sufficiently. Even if the laminated rings suffer circumferential length variations, and have relatively small circumferential lengths, the laminated rings can easily be held by the respective collets when the collets are radially contracted. Even when the laminated rings are radially spread, since the annular hoop of elements is sufficiently reduced in diameter by the element pressing means, the distance by which the laminated rings are radially spread by the collets may be relatively small, and the laminated rings can smoothly be inserted into the recesses in the elements.
Each of the elements has a pair of slanted edges on the head which are tapered toward a center thereof, and a pair of slanted edges on sides edges of the body which jointly make up a V-shaped surface for contacting the pulleys of the continuously variable transmission. The element pressing means comprises a first head holder having a first slanted surface for facing and slidably abutting against the lower slanted edges of the heads when the elements are held by the element holding means, and a second head holder disposed in alignment with the first head holder and having a second slanted surface for facing and slidably abutting against the upper slanted edges of the heads when the elements are held by the element holding means, the second head holder being movable toward the first head holder to reduce a spacing between the first slanted surface and the second slanted surface to press the heads of the elements in a direction toward the bodies thereof. The element holding means comprises a first body holder having a first slanted surface for facing and slidably abutting against the lower slanted edges of the bodies, the first body holder being vertically movable, and a second body holder disposed in alignment with the first body holder and having a second slanted surface for facing and slidably abutting against the upper slanted edges of the bodies, the second body holder being vertically movable.
The bodies of the elements are sandwiched and held between the first and second body holders of the element holding means, and the heads of the elements are sandwiched and held between the first and second head holders of the element pressing means. The second head holder is displaced toward the first head holder to press the heads of the elements toward the bodies thereof thereby to clamp the heads. Specifically, when the heads of the elements are sandwiched between the first and second head holders and the second head holder is displaced toward the first head holder, the upper slanted edges of the heads slide along the second slanted surface of the second head holder, and at the same time, the lower slanted edges of the heads slide along the first slanted surface of the first head holder, so that the heads of the elements are pressed toward the bodies thereof. As the bodies are thus displaced, the first body holder and the second body holder are also displaced to keep the bodies held thereby.
Since the elements are pressed by the first and second head holders at the slanted edges of the heads and the elements are pressed and reliably clamped simply by moving the first and second head holders toward each other, the apparatus is relatively simple in construction.
The apparatus should preferably further comprise load detecting means for detecting a load applied to the laminated rings when the laminated rings are pressed by the first ring pressing means and the second ring pressing means. When the laminated rings are inserted into the recesses in the elements, a load applied to the laminated rings can be detected while the laminated rings are being pressed into the recesses. If the load imposed on the laminated rings is excessively large, then it can be determined that the laminated rings may be causing scoring in the recesses or the diameters of the laminated rings may not be matching those of the recesses. Therefore, defective laminated rings can be rejected by detecting such as load.
According to yet another aspect of the present invention, there is also provided a method of manufacturing a belt for use in a continuously variable transmission which comprises an annular hoop of laminated metal elements each having a body and a head joined thereto with a pair of recesses defined therebetween, and a pair of rings inserted respectively in the recesses and each comprising a plurality of laminated metal web-shaped rings, comprising the steps of training the belt around a drive roller and a driven roller, displacing the drive roller and the driven roller away from each other to tension the belt, rotating the belt to break in the belt until the belt is rotated smoothly, pressing a portion of the belt between the drive roller and the driven roller while the belt is at rest or in rotation, and measuring a distance by which the belt is flexed when the portion of the belt between the drive roller and the driven roller is pressed, for thereby deciding whether the belt is acceptable or not.
After the belt is rotated under tension and broken in, the portion of the belt between the drive roller and the driven roller is pressed, and a distance by which the belt is flexed is measured. The measured distance is compared with a reference distance by which a normal belt whose clearances between the elements are appropriate and which has a required number of elements is flexed. In this manner, it can be decided whether the belt is acceptable or not. Consequently, assembled belts can efficiently be inspected with stable accuracy without inspection personnel differences and different skill levels.
Preferably, the method may further comprise the steps of positioning the drive roller and the driven roller in vertically spaced relationship to each other, and horizontally pressing the portion of the belt between the drive roller and the driven roller to decide whether the belt is acceptable or not. The portion of the belt between the drive roller and the driven roller extends substantially vertically, and a distance by which the belt is flexed when the portion of the belt between the drive roller and the driven roller is horizontally pushed is measured. Therefore, the distance by which the belt is flexed can accurately be measured. Accordingly, the assembled belt can reliably be determined as acceptable or not.
According to yet still another aspect of the present invention, there is also provided an apparatus for manufacturing a belt for use in a continuously variable transmission which comprises an annular hoop of laminated metal elements each having a body and a head joined thereto with a pair of recesses defined therebetween, and a pair of rings inserted respectively in the recesses and each comprising a plurality of laminated metal web-shaped rings, comprising an inspecting apparatus for inspecting the belt, the inspecting apparatus comprising a drive roller and a driven roller for training the belt therearound, tension applying means for displacing the drive roller and the driven roller away from each other to tension the belt, an actuator for actuating the drive roller to rotate the belt which is tensioned, pressing means for pressing a portion of the belt positioned between the drive roller and the driven roller, and measuring means for measuring a distance by which the belt is flexed when pressed by the pressing means.
Preferably, the drive roller and the driven roller are positioned in vertically spaced relationship to each other, the pressing means being disposed in confronting relationship to the portion of the belt positioned between the drive roller and the driven roller, the pressing means being horizontally movable.